add readline completion tip to phpdbginit

.phpdbginit

@@ -31,6 +31,18 @@ function my_debugging_function()
 /* phpdbg_break(PHPDBG_METHOD, "phpdbg::method"); */
 /* phpdbg_break(PHPDBG_FUNC, "my_global_function"); */
 /* phpdbg_break(PHPDBG_FILE, "/path/to/file.php:10"); */
+
+/*
+ If readline is loaded, you might want to setup completion for your project:
+*/
+if (function_exists('readline_completion_function')) {
+	readline_completion_function(function(){
+		return array_merge(
+			get_defined_functions()['user'],
+			array_keys(get_defined_constants())
+		);
+	});
+}
 :>
 ##########################################################
 # Now carry on initializing phpdbg ...